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iova_stress

DMA_MAP / DMA_UNMAP 4K page every 2M in IOVA SPACE for a given number of IOVA space terabytes.

Example usage

Find a suitable device:

# lspci -v
  02:00.1 Ethernet controller: Intel Corporation Ethernet Adaptive Virtual Function (rev 11)
        Subsystem: Google, Inc. Device 00c3
        Flags: fast devsel, NUMA node 0, IOMMU group 83
        Memory at 3224d000000 (64-bit, prefetchable) [virtual] [size=4M]
        Memory at 32311d20000 (64-bit, prefetchable) [virtual] [size=64K]
        Capabilities: [b0] MSI-X: Enable- Count=2048 Masked-
        Capabilities: [70] Express Endpoint, MSI 00
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [148] Alternative Routing-ID Interpretation (ARI)
        Capabilities: [158] Transaction Processing Hints
        Capabilities: [2ec] Access Control Services
        Capabilities: [1e4] Address Translation Service (ATS)

Get vendor id for this device:

# lspci -n -s 0000:02:00.1
   02:00.1 0200: 8086:1889 (rev 11)

Add it to a vfio-pci:

echo 8086 1889 > /sys/bus/pci/drivers/vfio-pci/new_id

Use vfio_new_id

Alternativly to the above, use vfio_new_id script to add vfio ids for each device in the system.

# vfio_new_id

Build iova_stress

$ make
cc -o iova_stress -static -Os iova_stress.c

Run this test with IOMMU group 83, and max iova space = 16T

Kernel: 6.7, Driver: Intel IOMMU:

yqbtg12:/home# ./iova_stress -s 16 -g 83
dma_size:       4K iova space: 16T iommu: ~  32783M time:   22.297s

Above example show that iommu page table uses approxemetly 32G of system memoery when 16T of IOVA space is touched.